Thesis (M.S.)--Naval Postgraduate School, 1966. / Thesis advisor(s): Haderlie, Eugene C. Cover title. "May 1966." Includes bibliographical references (p. 44).

Thesis (Ph. D.)--University of Washington, 1997. / Vita. Includes bibliographical references (leaves [186]-190).

Thesis (Ph. D.)--Michigan State University. Dept. of Environmental Engineering, 2008. / Title from PDF t.p. (viewed Aug. 18, 2009). Includes bibliographical references. Also issued in print.

Thesis (Ph.D.)--Hong Kong University of Science and Technology, 2006. / Includes bibliographical references. Also available in electronic version.

Sessile marine invertebrate larvae can recognize suitable settlement substrata by using various environmental cues, including organic/microbial "biofilms". In laboratory assays the effect of biofilm age on the settlement of a range of fouling species was assessed: the species included barnacle, bryozoan, spirorbin and ascidian larvae. The larvae of most species responded differentially to films of varying ages. A general trend of reversal of the effect of filming on the settlement response of the barnacle Balanus amphitrite amphitrite- from inhibitory to facilitatory - was noted with increasing film age. The settlement of the solitary ascidian Ciona intestinalis clearly was facilitated on filmed substrata of all ages. The larvae of the arborescent bryozoan Bugula flabellata generally were inhibited by biofilming (irrespective of film age), and the settlement of the polychaete Spirorbis spirorbis was found to be enhanced on "older" (12d) films only. In a series of manipulative panel experiments in a tidal rapid on the west coast of Scotland the effects of biofilming on subsequent larval settlement in the field were quantified. Inhibitory and facilitatory responses to biofilming were noted and these varied markedly between species and between two local habitats of contrasting flow regimes. The larvae of certain year-round settling species were found to vary in their response to biofilmed substrata depending on the season. Quantitative data were obtained for biofilms on artificial substrata by enumerating bacteria, diatoms, protozoans, fungi and the percent cover of microbial exopolymeric substances. These permitted comparisons of biofilms both in field and laboratory experiments. The results of the present study emphasize the importance of microbial surface film cues in explaining recruitment patterns of macrofouling assemblages during the first stages of substratum colonization.

No description available.

>Magister Scientiae - MSc / Membrane separation processes have been widely applied in the treatment of wastewater with polysulfone (PSF) polymer membrane being the most frequently used in ultrafiltration of wastewater due to its chemical and structural stability and mechanical robustness. The disadvantage to these membranes is their hydrophobicity which leads to membrane fouling caused by organic pollutants in water. Many studies have been conducted to increase the hydrophilic properties of the polysulfone membrane surface. Most recently metal oxide nanoparticles have been introduced to the polymer matrix in order to reduce membrane fouling and increase its hydrophilicity with measurable success. Natural organic matters are the one of the major fouling agents during ultrafiltration, reverse osmosis and microfiltration. Two organic acids (Tannic Acid and Alginic Acid) were selected to test the fouling behaviour of nanometallic synthesised polysulfone membranes. For this study, polysulfone casting suspension was prepared by dissolving polysulfone beads in N,N-dimethly acetamide. Three metallic nanoparticles of Silver, Cobalt and Nickel were selected to improve the hydrophilicity of the polysulfone membrane. The metal nanoparticles were prepared using the chemical reduction method. Cobalt nanoparticles were synthesized by dissolving the cobalt chloride salt in deionized water and reduced with sodium borohydride at room temperature. The nickel chloride salt was dissolved in ethanol and reduced with sodium borohydride under magnetic stirrer. Silver nanoparticles were prepared by dissolving the silver nitrate in deionised water and heated to boil, the sodium citrate was added to reduced the silver nitrate. These nanoparticles were then integrated into the polysulfone polymer matrix to form the metal nanoparticle polysulfone nanocomposites. This study focused on four prepared polysulfone nanocomposite membrane; 1 unmodified polysulfone (PSF), 2 polysulfone modified with cobalt nanoparticles (PSF/Co), 3 polysulfone modified with nickel nanoparticles (PSF/Ni) and 4 polysulfone modified with silver nanoparticles (PSF/Ag).

Chemical reaction fouling is one of several categories of fouling of heat exchangers. It is encountered mostly in petroleum, petrochemical, and food processing industries, where it results in severe economic penalties. Olefins have been associated with fouling during heating of organic mixtures, and gum formation during storage and use of hydrocarbon fuels. In this work, thermal fouling studies are reported for a number of olefins, present at 10 % wt. in kerosene, undergoing sensible heating in the liquid phase at relatively high heat fluxes. Experimental work was done on an available fouling rig consisting of an annular probe and a coiled wire probe mounted in parallel. The annular probe with its heated central core operated in turbulent flow whilst the coiled wire, with flow normal to it, was in the laminar flow regime. Runs were conducted both under oxygenated (air-saturated) and deoxygenated conditions. The range of bulk temperatures was from 70 - 85 ℃, the initial wall temperatures were 180 - 205 °C, with a system pressure of 410 kPa (abs.). The range of heat fluxes was 150 - 350 kW/m². Only minor differences were noted between the extent or rate of fouling on the two different probes. Runs at heat fluxes below 180 kW/m² and bulk temperatures below 80 °C generally showed no measurable fouling with any of the olefins tested. Linear and falling rate fouling curves were observed at more severe conditions over 45 hours of typical runs. Under air saturated conditions, straight chain terminal olefins of C₈ - C₉ showed little or no measurable fouling. The longer chain length hexadecane-1, showed a significant increase in fouling. Moderate fouling was observed for 4-vinylcyclohexene. The cyclic olefins, dicyclopentadiene and indene, yielded the greatest R[formula omitted] values, being about 30 - 50 times those of the straight chain terminal olefins. Under deoxygenated conditions, typical R[formula omitted] values were a factor of about 30 below the corresponding values for air saturated conditions. R[formula omitted] generally increased with increasing heat flux. Where the antioxidant initially present in the olefin was not removed before use, very little fouling occurred. The effects of deoxygenation, heat flux and species effects are discussed and a probable fouling mechanism involving formation of polymeric peroxides by autoxidation of the olefins suggested. The fouling rates over the linear portions of the fouling curves have been calculated and the deposit thermal conductivity based on the maximum fouling resistance and deposit thickness have been estimated. Analyses of selected deposits have been presented and compared with both theoretical calculations for the expected polymeric peroxides and values in the literature. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

Biofouling has been an economically and environmentally costly problem to mankind ever since they set sail. Biofouling causes frictional drag leading to slow vessel speeds, and increased fuel costs. Antifouling (AF) coatings containing biocides have been used for decades, however, since some biocides have shown undesired effects towards the environment, a non-toxic solution to combat fouling is desired. Subsequently, fouling release (FR) coatings quickly gained acceptance as a non-toxic approach to contend with biofouling. Unlike AF coatings, FR coatings not necessarily prevent settlement of organisms, they permit weak adhesion which is easily released by water shear or light grooming. The siloxane-polyurethane (SiPU) coatings based on the concept of self-stratification is a non-toxic and durable approach to prepare FR coatings. In this work, several approaches were considered to optimize surface properties of SiPU coatings. Incorporation of phenyl-methyl silicone oils led to improved FR properties towards several marine organisms in laboratory assays and in ocean field immersion. Enhancement in FR properties may be attributed to slowly exuding silicone oil providing surface lubricity, weakening the adhesion of marine organisms. Addition of diphenyldimethyl siloxane in to SiPU coatings at different ratios resulted in micro-scale surface topographical features which negatively affected microfouling-release while several coatings displayed good FR performance towards macrofouling organisms. In another study, decreasing the acid group content helped to improve FR performance towards barnacles, but FR performance towards diatoms were compromised. Novel amphiphilic siloxane-polyurethane (AmSiPU) coatings from polyisocyanate pre-polymers modified with polydimethyl siloxane and polyethylene glycol displayed excellent FR properties towards several marine organisms during laboratory assays. These AmSiPU coatings show promise as contenders to commercial FR standards. Initial development of SiPU coatings with hydrophilic surfaces showed promise, as the coatings showed rapidly rearranging surfaces with comparable FR performance to commercial standards which claim hydrophilic surface properties. During freshwater field immersion trials, SiPU coatings displayed excellent mussel FR performance up to 3 years. Surface analysis suggested that solvent content affected self-stratification and morphology of SiPU coatings. The SiPU coating system is a highly tunable, tough, environmentally friendly, and practical FR solution which can evolve along with non-toxic commercial marine coatings. / Office of Naval Research (Grant number N00014-12-1-0482) / SSPC / Valpar / American Coatings Association / North Dakota State University. College of Science and Mathematics

A major challenge facing widespread implementation of membrane-based water purification is fouling, which results in increased operating costs and reduced membrane lifetime. This thesis focuses on various methods, including novel membrane surface modifications and polymers that resist degradation when exposed to oxidizing agents used as disinfectants, to alleviate membrane fouling. Fouling-resistant ultrafiltration membrane coatings were prepared from poly(ethylene glycol) diglycidyl ether-crosslinked chitosan (chi-PEG hybrid). Composite membranes were prepared for oil-water emulsion filtration by coating the most promising chi-PEG hybrid onto a polysulfone ultrafiltration membrane. Optimization of the coating layer thickness led to composite membranes that exhibited water flux values more than 5 times higher than that of uncoated membranes after one day of oily-water crossflow filtration. The organic rejection of the coated membranes was also higher than that of the uncoated polysulfone membranes. Polydopamine (PDOPA) deposition was discovered to reduce fouling in water purification membranes. PDOPA was found to deposit from solution onto virtually any surface. When deposited on water purification membranes, PDOPA rendered the membrane more hydrophilic and less susceptible to fouling. Moreover, covalent binding of other molecules, such as amine-terminated poly (ethylene glycol) (PEG), to PDOPA is simple and performed using benign chemicals and conditions. Commercially-available polymeric membranes were modified with polydopamine, and all showed improved fouling resistance while filtering oil-water emulsions. To demonstrate the versatility and ease of PDOPA modification scalability, PDOPA was deposited on entire membrane modules, and the resulting modified module exhibited improved fouling resistance. Finally, high ion rejection, chlorine-tolerant sulfonated polysulfone thin-film composite membranes were prepared and characterized. Interestingly, freestanding thick sulfonated poly(arylene ether sulfone) (BPS) films exhibit nearly neutral electrostatic charge, even though sulfonation introduces fixed negative charge into the polymer structure. As a result, charge exclusion ion partitioning is not a dominant rejection mechanism in these films. However, composite membranes prepared from a BPS coating layer and a porous Udel polysulfone support exhibit a negatively charged surface and, presumably, charge exclusion would be a more important partitioning mechanism for these membranes. Therefore, thick BPS films do not exhibit certain drawbacks, such as reduced salt rejection of mixed-valence feeds, that are observed in BPS thin-film composite membranes. / text